Digital cameras are well known. As their cost drops, digital cameras continue to grow in popularity. Digital cameras eliminate the need to purchase film and have it developed. They also greatly reduce the need to have prints made, since digital images can easily be viewed on a computer monitor or the like. Digital cameras have thus reduced the overall cost of photography.
One rapidly growing application for digital cameras is their use in personal electronic devices, such as cellular telephones. Camera phones outsold other digital cameras for the first time in the last quarter of 2003. Camera phones enable pictures to be conveniently and rapidly shared with others. Images can be captured on the spur of the moment and then easily communicated to others via the cellular telephone network and/or via the Internet.
Although such contemporary camera phones have proven generally suitable for their intended purposes, they possess inherent deficiencies that detract from their overall effectiveness and desirability. For example, contemporary digital cameras commonly have variable focus. However, contemporary camera phones do not have this desirable feature. Contemporary variable focus mechanisms are simply too bulky for today's compact camera phones.
Consequently, contemporary camera phones have fixed focuses. Although a fixed focus can sometimes be adequate under good lighting conditions, a fixed focus generally does not perform well when the camera is used in low light conditions. A fixed focus mechanism approximates a pinhole lens to provide sufficient depth of field so as to remain in focus, at least to some degree, regardless of the distance between the subject and the camera. However, such a stopped-down lens is undesirably sensitive to ambient lighting conditions. This is because the near pin-hole lens of a fixed focus camera does not admit much light. Thus, such fixed focus cameras generally require more light than variable focus cameras. In addition, the small aperture of a pin-hole lens limits the resolution of the camera, due to the diffraction limit of light. Thus, such fixed focus cameras generally have lower resolution than variable focus cameras.
When there is insufficient ambient lighting, the image tends to appear undesirably dark. In recognizing the limitations of contemporary camera phones using such fixed focus lenses, the prior art has provided flash mechanisms in an attempt to insure that adequate light is provided. However, cellular telephones use battery power supplies, and thus have limited power available for the use of such flash mechanisms. More frequent use of the flash to take photographs thus results in the need to more frequently charge the camera phone. Of course, frequent recharging is undesirable.
As such, it is desirable to provide a miniature autofocus camera that is suitable for use in personal electronic devices, such as cellular telephones.